[Show abstract][Hide abstract] ABSTRACT: Background:
Tight junction (TJ) defects have recently been associated with asthma and chronic rhinosinusitis. The expression, function, and regulation of nasal epithelial TJs remain unknown in patients with allergic rhinitis (AR).
We investigated the expression, function, and regulation of TJs in the nasal epithelium of patients with house dust mite (HDM)-induced AR and in an HDM-induced murine model of allergic airway disease.
Air-liquid interface cultures of primary nasal epithelial cells of control subjects and patients with HDM-induced AR were used for measuring transepithelial resistance and passage to fluorescein isothiocyanate-dextran 4 kDa (FD4). Ex vivo transtissue resistance and FD4 permeability of nasal mucosal explants were measured. TJ expression was evaluated by using real-time quantitative PCR and immunofluorescence. In addition, the effects of IL-4, IFN-γ, and fluticasone propionate (FP) on nasal epithelial cells were investigated in vitro. An HDM murine model was used to study the effects of allergic inflammation and FP treatment on transmucosal passage of FD4 in vivo.
A decreased resistance in vitro and ex vivo was found in patients with HDM-induced AR, with increased FD4 permeability and reduced occludin and zonula occludens-1 expression. AR symptoms correlated inversely with resistance in patients with HDM-induced AR. In vitro IL-4 decreased transepithelial resistance and increased FD4 permeability, whereas IFN-γ had no effect. FP prevented IL-4-induced barrier dysfunction in vitro. In an HDM murine model FP prevented the allergen-induced increased mucosal permeability.
We found impaired nasal epithelial barrier function in patients with HDM-induced AR, with lower occludin and zonula occludens-1 expression. IL-4 disrupted epithelial integrity in vitro, and FP restored barrier function. Better understanding of nasal barrier regulation might lead to a better understanding and treatment of AR.
Full-text · Article · Feb 2016 · Journal of Allergy and Clinical Immunology
[Show abstract][Hide abstract] ABSTRACT: Idiopathic achalasia is a severe motility disorder of the esophagus and is characterized by a failure of the lower esophageal sphincter to relax due to a loss of neurons in the myenteric plexus. Most recently, we identified an eight-amino-acid insertion in the cytoplasmic tail of HLA-DQβ1 as strong achalasia risk factor in a sample set from Central Europe, Italy and Spain. Here, we tested whether the HLA-DQβ1 insertion also confers achalasia risk in the Polish and Swedish population. We could replicate the initial findings and the insertion shows strong achalasia association in both samples (Poland P=1.84 × 10(-04), Sweden P=7.44 × 10(-05)). Combining all five European data sets - Central Europe, Italy, Spain, Poland and Sweden - the insertion is achalasia associated with Pcombined=1.67 × 10(-35). In addition, we observe that the frequency of the insertion shows a geospatial north-south gradient. The insertion is less common in northern (around 6-7% in patients and 2% in controls from Sweden and Poland) compared with southern Europeans (~16% in patients and 8% in controls from Italy) and shows a stronger attributable risk in the southern European population. Our study provides evidence that the prevalence of achalasia may differ between populations.European Journal of Human Genetics advance online publication, 6 January 2016; doi:10.1038/ejhg.2015.262.
No preview · Article · Jan 2016 · European journal of human genetics: EJHG
[Show abstract][Hide abstract] ABSTRACT: Inflammatory bowel diseases (IBD), consisting of ulcerative colitis (UC) and Crohn's disease (CD), are chronic immune-mediated diseases of the gut. Here, the potential role of mast cells (MC) is discussed, mainly focusing on preclinical studies. MC can be activated by antigen-mediated crosslinking of immunoglobulin receptors, by free light chains of immunoglobulins, stress and ATP. Upon activation, MC release bioactive mediators, of which the serine proteases mMCP-6 and Prss31 were shown to be involved in the development of acute colitis. Inhibition of MCs by activation of the inhibitory receptor LIMR3 or inhibitors of proteases may therefore represent new therapeutic targets to treat IBD. Human data are however lacking.
No preview · Article · Dec 2015 · Current Opinion in Pharmacology
[Show abstract][Hide abstract] ABSTRACT: Background:
The calcium-sensing receptor (CaSR) is a calcium (Ca(2+)) sensitive G protein-coupled receptor implicated in various biological processes. In particular, it regulates Ca(2+)/Mg(2+)- homeostasis and senses interstitial Ca(2+) levels and thereby controls downstream signalling cascades. Due to its expression in the gut epithelium, the enteric nervous system and smooth muscles and its key function in regulation and coordination of muscular contraction and secretion, it represents an excellent candidate gene to be investigated in the pathophysiology of irritable bowel syndrome (IBS). Disturbed CaSR structure and function may impact gastrointestinal regulation of muscular contraction, neuronal excitation and secretion and consequently contribute to symptoms seen in IBS, such as disordered defecation as well as disturbed gut motility and visceral sensitivity.
We have therefore genotyped the functional CASR SNP rs1801725 in three case control samples from the UK, Belgium and the USA.
Genotype frequencies showed no association in the three genotyped case-control samples, neither with IBS nor with IBS subtypes.
Although we could not associate the SNP to any of the established bowel symptom based IBS subtypes we cannot rule out association to altered Ca(2+) levels and disturbed secretion and gut motility which were unfortunately not assessed in the patients genotyped. This underlines the necessity of a more detailed phenotyping of IBS patients and control individuals in future studies.
Full-text · Article · Dec 2015 · BMC Medical Genetics
[Show abstract][Hide abstract] ABSTRACT: Objective Achalasia is a chronic motility disorder of the oesophagus for which laparoscopic Heller myotomy (LHM) and endoscopic pneumodilation (PD) are the most commonly used treatments. However, prospective data comparing their long-term efficacy is lacking.
Design 201 newly diagnosed patients with achalasia were randomly assigned to PD (n=96) or LHM (n=105). Before randomisation, symptoms were assessed using the Eckardt score, functional test were performed and quality of life was assessed. The primary outcome was therapeutic success (presence of Eckardt score ≤3) at the yearly follow-up assessment. The secondary outcomes included the need for re-treatment, lower oesophageal sphincter pressure, oesophageal emptying and the rate of complications.
Results In the full analysis set, there was no significant difference in success rate between the two treatments with 84% and 82% success after 5 years for LHM and PD, respectively (p=0.92, log-rank test). Similar results were obtained in the per-protocol analysis (5-year success rates: 82% for LHM vs 91% for PD, p=0.08, log-rank test). After 5 years, no differences in secondary outcome parameter were observed. Redilation was performed in 24 (25%) of PD patients. Five oesophageal perforations occurred during PD (5%) while 12 mucosal tears (11%) occurred during LHM.
Conclusions After at least 5 years of follow-up, PD and LHM have a comparable success rate with no differences in oesophageal function and emptying. However, 25% of PD patients require redilation during follow-up. Based on these data, we conclude that either treatment can be proposed as initial treatment for achalasia.
Trial registration numbers Netherlands trial register (NTR37) and Current Controlled Trials registry (ISRCTN56304564).
[Show abstract][Hide abstract] ABSTRACT: One of the main tasks of the immune system is to discriminate and appropriately react to “danger” or “non-danger” signals. This is crucial in the gastrointestinal tract, where the immune system is confronted with a myriad of food antigens and symbiotic microflora that are in constant contact with the mucosa, in addition to any potential pathogens. This large number of antigens and commensal microflora, which are essential for providing vital nutrients, must be tolerated by the intestinal immune system to prevent aberrant inflammation. Hence, the balance between immune activation versus tolerance should be tightly regulated to maintain intestinal homeostasis and to prevent immune activation indiscriminately against all luminal antigens. Loss of this delicate equilibrium can lead to chronic activation of the intestinal immune response resulting in intestinal disorders, such as inflammatory bowel diseases (IBD). In order to maintain homeostasis, the immune system has evolved diverse regulatory strategies including additional non-immunological actors able to control the immune response. Accumulating evidence strongly indicates a bidirectional link between the two systems in which the brain modulates the immune response via the detection of circulating cytokines and via direct afferent input from sensory fibers and from enteric neurons. In the current review, we will highlight the most recent findings regarding the cross-talk between the nervous system and the mucosal immune system and will discuss the potential use of these neuronal circuits and neuromediators as novel therapeutic tools to reestablish immune tolerance and treat intestinal chronic inflammation.
Preview · Article · Nov 2015 · Frontiers in Immunology
[Show abstract][Hide abstract] ABSTRACT: Objective:
Functional dyspepsia (FD) is a chronic gastroduodenal disorder. Individuals with FD demonstrate visceral hypersensitivity, abnormal central pain processing, and low mood, but it is unclear whether psychotropic drugs are an effective treatment for the condition. We performed a systematic review and meta-analysis of randomised controlled trials (RCTs).
MEDLINE, EMBASE, EMBASE Classic, PsychINFO and the Cochrane Controlled Trials Register were searched (up to June 2015) for RCTs recruiting adults with FD comparing psychotropic drugs with placebo. We contacted authors directly to maximise trial eligibility and minimise risk of bias for studies. Dichotomous symptom data were pooled to obtain relative risk (RR) of remaining symptomatic after therapy, with 95% CIs.
The search identified 2795 citations; 13 RCTs (1241 patients) were eligible. Ten trials were at low risk of bias. The RR of FD symptoms not improving with psychotropic drugs versus placebo was 0.78 (95% CI 0.68 to 0.91) (number needed to treat=6; 95% CI 4 to 16). However, benefit was limited to antipsychotics and tricyclic antidepressants. When only studies that excluded individuals with coexistent mood disorder were considered, there was no benefit. Total numbers of adverse events and adverse events leading to withdrawal were significantly more common, with a number needed to harm of 21 for both.
Psychotropic drugs may be an effective treatment for FD, but the effect appears to be limited to antipsychotics and tricyclic antidepressants with fewer trials for other agents, meaning that firm conclusions for efficacy cannot be made. More data from high quality RCTs are required to support their use in the treatment of FD.
[Show abstract][Hide abstract] ABSTRACT: Intestinal macrophages are strategically located in different layers of the intestine, including the mucosa, submucosa and muscularis externa, where they perform complex tasks to maintain intestinal homeostasis. As the gastrointestinal tract is continuously challenged by foreign antigens, macrophage activation should be tightly controlled to prevent chronic inflammation and tissue damage. Unraveling the precise cellular and molecular mechanisms underlying the tissue-specific control of macrophage activation is crucial to get more insight into intestinal immune regulation. Two recent reports provide unanticipated evidence that the enteric nervous system (ENS) acts as a critical regulator of macrophage function in the myenteric plexus. Both studies clearly illustrate that enteric neurons reciprocally interact with intestinal macrophages and are actively involved in shaping their phenotype. This concept has striking parallels with the central nervous system (CNS), where neuronal signals maintain microglia, the resident macrophages of the CNS, in a quiescent, anti-inflammatory state. This inevitably evokes the perception that the ENS and CNS share mechanisms of neuroimmune interaction. In line, intestinal macrophages, both in the muscularis externa and (sub)mucosa, express high levels of CX3CR1, a feature that was once believed to be unique for microglia. CX3CR1 is the sole receptor of fractalkine (CX3CL1), a factor mainly produced by neurons in the CNS to facilitate neuron-microglia communication. The striking parallels between resident macrophages of the brain and intestine might provide a promising new line of thought to get more insight into cellular and molecular mechanisms controlling macrophage activation in the gut.
Full-text · Article · Nov 2015 · Frontiers in Cellular Neuroscience
[Show abstract][Hide abstract] ABSTRACT: Background:
During abdominal sepsis, the inhibition of gastrointestinal (GI) motility together with mucosal barrier dysfunction will lead to increased bacterial translocation and maintenance of sepsis. The activation of the vagal anti-inflammatory pathway remains an appealing therapeutic strategy in sepsis. In this respect, selective alpha7 nicotinic acetylcholine receptor (α7nAChR) agonists have shown anti-inflammatory properties in several animal models of inflammation.
Sepsis was induced in OF-1 mice by caecal ligation and puncture (CLP). GI transit was quantified, and cytokine levels were determined in serum and colon. Colonic permeability was assessed by means of Evans blue injection. We studied the effect of GTS-21, an α7nAChR agonist on the aforementioned parameters. Splenectomized animals as well as α7nAChR-knock-out animals (Chrna7) were included to study the role of splenic macrophages and the α7nAChR during polymicrobial abdominal sepsis.
In septic animals, GTS-21 significantly ameliorated GI motility, lowered systemic and colonic levels of IL-6, decreased colonic permeability and decreased the number of positive cultures obtained from blood and mesenteric lymph nodes. Splenectomy prevented animals from developing sepsis-induced ileus. Chrna7 mice displayed a more severe septic phenotype, whereas GTS-21 remarkably was also beneficial in these animals.
Our results show that peripheral targeting of the vagal anti-inflammatory pathway proves beneficial in an animal model of polymicrobial abdominal sepsis. A major role is allocated to splenic immune cells in the development of sepsis, as preventive splenectomy was protective for the development of sepsis. Data on the Chrna7 mice suggest that the beneficial effects mediated by GTS-21 on inflammation and motility might be related to activation of other receptors besides the α7nAChR.
[Show abstract][Hide abstract] ABSTRACT: Human leukocyte antigen (HLA) genes confer substantial risk for autoimmune diseases on a log-additive scale. Here we speculated that differences in autoantigen-binding repertoires between a heterozygote's two expressed HLA variants might result in additional non-additive risk effects. We tested the non-additive disease contributions of classical HLA alleles in patients and matched controls for five common autoimmune diseases: rheumatoid arthritis (ncases = 5,337), type 1 diabetes (T1D; ncases = 5,567), psoriasis vulgaris (ncases = 3,089), idiopathic achalasia (ncases = 727) and celiac disease (ncases = 11,115). In four of the five diseases, we observed highly significant, non-additive dominance effects (rheumatoid arthritis, P = 2.5 × 10(-12); T1D, P = 2.4 × 10(-10); psoriasis, P = 5.9 × 10(-6); celiac disease, P = 1.2 × 10(-87)). In three of these diseases, the non-additive dominance effects were explained by interactions between specific classical HLA alleles (rheumatoid arthritis, P = 1.8 × 10(-3); T1D, P = 8.6 × 10(-27); celiac disease, P = 6.0 × 10(-100)). These interactions generally increased disease risk and explained moderate but significant fractions of phenotypic variance (rheumatoid arthritis, 1.4%; T1D, 4.0%; celiac disease, 4.1%) beyond a simple additive model.
[Show abstract][Hide abstract] ABSTRACT: Psychological factors increase the risk to develop postinfectious IBS (PI-IBS), but the mechanisms involved are unclear. As stress affects the immune system, we investigated the potential interaction between psychological factors, the immune response against infectious gastroenteritis (IGE) and the development of IGE and PI-IBS in a large cohort exposed to contaminated drinking water.
18 620 people exposed to contaminated drinking water (norovirus, Giardia lamblia, Campylobacter jejuni) were invited to participate in a prospective controlled cohort study. They were asked to complete questionnaires assessing demographic, psychological and clinical data during the outbreak and 1 year later. At both time points, in-depth immune function (peripheral blood and rectal biopsies) was studied in a subgroup of subjects.
1379 subjects completed the questionnaires during the outbreak, of which 271 developed IGE. Risk factors for IGE included younger age, pre-existing dyspepsia-like symptoms, anxiety and drinking contaminated tap water. Anxiety scores before the outbreak inversely correlated with interleukin-2-expressing CD4+ T cells (r=0.6, p=0.01, n=23). At follow-up, 34 of 172 (20%) IGE subjects developed IBS compared with 24/366 exposed participants (7%, p<0.0001, χ(2) test). A Th2 cytokine phenotype at time of infection was associated with increased risk for PI-IBS 1 year later. Except for increased B cell numbers, no evidence for systemic or rectal mucosal immune activation in PI-IBS was demonstrated at follow-up.
Our study shows that the increased risk of patients with psychological comorbidity to develop PI-IBS may partly result from an increased susceptibility to develop IGE, possibly resulting from a Th2-immune bias.
Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.